It’s that time of year when the greening of the Fescue Belt may soon give way to the yellowing of the same region, at least in many pastures and hayfields.

Buttercup species only offer eye appeal to those passersby who don’t have any skin in the livestock production game. For those who do, they often comprise the bulk of the enemy in the annual spring weed war.

“As a cool-season weed, buttercup often flourishes in overgrazed pasture fields with poor stands of desirable forages,” notes J.D. Green. The extension weed scientist with the University of Kentucky explains that the problem is made worse when fields are heavily grazed by animals from fall through early spring.

Most buttercups have a winter-annual life cycle, but some species are classified as short-lived perennials. Green says that buttercups are generally characterized by producing five, shiny yellow petals in the spring; however, different species vary in their vegetative leaf characteristics.

“New seed begins to develop during the time petals are showing,” Green explains. “Waiting until after flowers appear can be too late to implement control tactics. This is one reason why new plants emerge each year,” he adds.

Most buttercup plants develop from seed during the late winter months when temperatures begin to warm, but some will emerge in the fall. Pasture management practices that improve and promote growth of desirable plants during these months will provide the needed competition against buttercup emergence and growth. If livestock are allowed to overgraze fields during the fall and winter months, buttercup plants can quickly overtake a pasture.

“Mowing fields or clipping plants close to the ground in the early spring, before buttercup plants can produce flowers, may help reduce the number of new seeds produced, but mowing alone will not totally eliminate seed production,” Green asserts.

Herbicide help

Many pasture managers rely on chemicals to keep buttercups in check. Green says that 2,4-D products labeled for use on grazed grass pastures will effectively control buttercup. Depending on other weeds present, herbicides that contain dicamba+2,4-D (for example, Weedmaster, Brash, and Rifle-D), aminopyralid (for example, GrazonNext and Duracor), triclopyr (Crossbow), or metsulfuron (Cimarron) can also be used.

Legumes, such as clovers interseeded with grass pastures, will be severely injured or killed by many of these broadleaf-killing herbicide products. Green suggests applying the herbicide in the early spring (March or early April) before flowers are observed, when buttercup plants are still small and actively growing in a vegetative growth stage.

To maximize herbicide activity, wait until daytime air temperatures are greater than 55°F for two to three consecutive days. Be sure to consult the herbicide label for information on grazing restrictions, precautions, or other possible limitations.

“For fields heavily infested with buttercup, a variety of control tactics may be needed,” Green notes. He recommends applying an herbicide to help reduce the population of buttercup plants in the spring, then employ good pasture strategies throughout the year to help improve and thicken the stand of desirable forages. Finally, don’t overgraze pastures in the fall and early winter.